Created attachment 153444 [details] screenshot of the current error If you try to install a font but it's already present on the system you get a dialog with "Error" as a heading and a long file:// link before the explanation. It looks like something terrible just happened. Suggestion: Have it with a dialog-information icon and clear text: **This font is already installed.** "The font Fontname is already present on the system."
File link may help in some cases when user does not know where this font is installed (but need this information). However, it's true only if error message shows the already installed file and not the new file.